A hot, dry combustion gas at 600 ◦C and 1 bar flows over the wall of a combustion chamber. To prevent the wall temperature from rising too much, water is blown through the porous wall of the chamber,...

A hot, dry combustion gas at 600 ◦C and 1 bar flows over the wall of a combustion chamber. To prevent the wall temperature from rising too much, water is blown through the porous wall of the chamber, Fig. 1.61, and then evaporates, which reduces the wall

temperature. How low can the temperature of the wall become and how much water ˙m_A
in kg/m²s has to be fed into the chamber to achieve this temperature reduction? Given: M˜_Acβ_mc_pA/α_m
= 1.3, M˜_B
= 28.953 kg/kmol, M˜_A
= 18.015 kg/kmol and ∆h_v
= 2346 kJ/kg, c_pA = 1.907 kJ/kgK. The heat transfer coefficient between the combustion gas and the water surface is αm = 120W/m2K.